<?php
/**
 * CSqliteSchema class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CSqliteSchema is the class for retrieving metadata information from a SQLite (2/3) database.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.db.schema.sqlite
 * @since 1.0
 */
class CSqliteSchema extends CDbSchema
{
    /**
     * @var array the abstract column types mapped to physical column types.
     * @since 1.1.6
     */
    public $columnTypes = array(
        'pk' => 'integer PRIMARY KEY AUTOINCREMENT NOT NULL',
        'string' => 'varchar(255)',
        'text' => 'text',
        'integer' => 'integer',
        'float' => 'float',
        'decimal' => 'decimal',
        'datetime' => 'datetime',
        'timestamp' => 'timestamp',
        'time' => 'time',
        'date' => 'date',
        'binary' => 'blob',
        'boolean' => 'tinyint(1)',
        'money' => 'decimal(19,4)',
    );

    /**
     * Resets the sequence value of a table's primary key.
     * The sequence will be reset such that the primary key of the next new row inserted
     * will have the specified value or max value of a primary key plus one (i.e. sequence trimming).
     * @param CDbTableSchema $table the table schema whose primary key sequence will be reset
     * @param integer|null $value the value for the primary key of the next new row inserted.
     * If this is not set, the next new row's primary key will have the max value of a primary
     * key plus one (i.e. sequence trimming).
     * @since 1.1
     */
    public function resetSequence($table, $value = null)
    {
        if ($table->sequenceName === null)
            return;
        if ($value !== null)
            $value = (int)($value) - 1;
        else
            $value = (int)$this->getDbConnection()
                ->createCommand("SELECT MAX(`{$table->primaryKey}`) FROM {$table->rawName}")
                ->queryScalar();
        try {
            // it's possible that 'sqlite_sequence' does not exist
            $this->getDbConnection()
                ->createCommand("UPDATE sqlite_sequence SET seq='$value' WHERE name='{$table->name}'")
                ->execute();
        } catch (Exception $e) {
        }
    }

    /**
     * Enables or disables integrity check. Note that this method used to do nothing before 1.1.14. Since 1.1.14
     * it changes integrity check state as expected.
     * @param boolean $check whether to turn on or off the integrity check.
     * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
     * @since 1.1
     */
    public function checkIntegrity($check = true, $schema = '')
    {
        $this->getDbConnection()->createCommand('PRAGMA foreign_keys=' . (int)$check)->execute();
    }

    /**
     * Returns all table names in the database.
     * @param string $schema the schema of the tables. This is not used for sqlite database.
     * @return array all table names in the database.
     */
    protected function findTableNames($schema = '')
    {
        $sql = "SELECT DISTINCT tbl_name FROM sqlite_master WHERE tbl_name<>'sqlite_sequence'";
        return $this->getDbConnection()->createCommand($sql)->queryColumn();
    }

    /**
     * Creates a command builder for the database.
     * @return CSqliteCommandBuilder command builder instance
     */
    protected function createCommandBuilder()
    {
        return new CSqliteCommandBuilder($this);
    }

    /**
     * Loads the metadata for the specified table.
     * @param string $name table name
     * @return CDbTableSchema driver dependent table metadata. Null if the table does not exist.
     */
    protected function loadTable($name)
    {
        $table = new CDbTableSchema;
        $table->name = $name;
        $table->rawName = $this->quoteTableName($name);

        if ($this->findColumns($table)) {
            $this->findConstraints($table);
            return $table;
        } else
            return null;
    }

    /**
     * Collects the table column metadata.
     * @param CDbTableSchema $table the table metadata
     * @return boolean whether the table exists in the database
     */
    protected function findColumns($table)
    {
        $sql = "PRAGMA table_info({$table->rawName})";
        $columns = $this->getDbConnection()->createCommand($sql)->queryAll();
        if (empty($columns))
            return false;

        foreach ($columns as $column) {
            $c = $this->createColumn($column);
            $table->columns[$c->name] = $c;
            if ($c->isPrimaryKey) {
                if ($table->primaryKey === null)
                    $table->primaryKey = $c->name;
                elseif (is_string($table->primaryKey))
                    $table->primaryKey = array($table->primaryKey, $c->name);
                else
                    $table->primaryKey[] = $c->name;
            }
        }
        if (is_string($table->primaryKey) && !strncasecmp($table->columns[$table->primaryKey]->dbType, 'int', 3)) {
            $table->sequenceName = '';
            $table->columns[$table->primaryKey]->autoIncrement = true;
        }

        return true;
    }

    /**
     * Collects the foreign key column details for the given table.
     * @param CDbTableSchema $table the table metadata
     */
    protected function findConstraints($table)
    {
        $foreignKeys = array();
        $sql = "PRAGMA foreign_key_list({$table->rawName})";
        $keys = $this->getDbConnection()->createCommand($sql)->queryAll();
        foreach ($keys as $key) {
            $column = $table->columns[$key['from']];
            $column->isForeignKey = true;
            $foreignKeys[$key['from']] = array($key['table'], $key['to']);
        }
        $table->foreignKeys = $foreignKeys;
    }

    /**
     * Creates a table column.
     * @param array $column column metadata
     * @return CDbColumnSchema normalized column metadata
     */
    protected function createColumn($column)
    {
        $c = new CSqliteColumnSchema;
        $c->name = $column['name'];
        $c->rawName = $this->quoteColumnName($c->name);
        $c->allowNull = !$column['notnull'];
        $c->isPrimaryKey = $column['pk'] != 0;
        $c->isForeignKey = false;
        $c->comment = null; // SQLite does not support column comments at all

        $c->init(strtolower($column['type']), $column['dflt_value']);
        return $c;
    }

    /**
     * Builds a SQL statement for renaming a DB table.
     * @param string $table the table to be renamed. The name will be properly quoted by the method.
     * @param string $newName the new table name. The name will be properly quoted by the method.
     * @return string the SQL statement for renaming a DB table.
     * @since 1.1.13
     */
    public function renameTable($table, $newName)
    {
        return 'ALTER TABLE ' . $this->quoteTableName($table) . ' RENAME TO ' . $this->quoteTableName($newName);
    }

    /**
     * Builds a SQL statement for truncating a DB table.
     * @param string $table the table to be truncated. The name will be properly quoted by the method.
     * @return string the SQL statement for truncating a DB table.
     * @since 1.1.6
     */
    public function truncateTable($table)
    {
        return "DELETE FROM " . $this->quoteTableName($table);
    }

    /**
     * Builds a SQL statement for dropping a DB column.
     * Because SQLite does not support dropping a DB column, calling this method will throw an exception.
     * @param string $table the table whose column is to be dropped. The name will be properly quoted by the method.
     * @param string $column the name of the column to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a DB column.
     * @since 1.1.6
     */
    public function dropColumn($table, $column)
    {
        throw new CDbException(Yii::t('yii', 'Dropping DB column is not supported by SQLite.'));
    }

    /**
     * Builds a SQL statement for renaming a column.
     * Because SQLite does not support renaming a DB column, calling this method will throw an exception.
     * @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
     * @param string $name the old name of the column. The name will be properly quoted by the method.
     * @param string $newName the new name of the column. The name will be properly quoted by the method.
     * @return string the SQL statement for renaming a DB column.
     * @since 1.1.6
     */
    public function renameColumn($table, $name, $newName)
    {
        throw new CDbException(Yii::t('yii', 'Renaming a DB column is not supported by SQLite.'));
    }

    /**
     * Builds a SQL statement for adding a foreign key constraint to an existing table.
     * Because SQLite does not support adding foreign key to an existing table, calling this method will throw an exception.
     * @param string $name the name of the foreign key constraint.
     * @param string $table the table that the foreign key constraint will be added to.
     * @param string $columns the name of the column to that the constraint will be added on. If there are multiple columns, separate them with commas.
     * @param string $refTable the table that the foreign key references to.
     * @param string $refColumns the name of the column that the foreign key references to. If there are multiple columns, separate them with commas.
     * @param string $delete the ON DELETE option. Most DBMS support these options: RESTRICT, CASCADE, NO ACTION, SET DEFAULT, SET NULL
     * @param string $update the ON UPDATE option. Most DBMS support these options: RESTRICT, CASCADE, NO ACTION, SET DEFAULT, SET NULL
     * @return string the SQL statement for adding a foreign key constraint to an existing table.
     * @since 1.1.6
     */
    public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete = null, $update = null)
    {
        throw new CDbException(Yii::t('yii', 'Adding a foreign key constraint to an existing table is not supported by SQLite.'));
    }

    /**
     * Builds a SQL statement for dropping a foreign key constraint.
     * Because SQLite does not support dropping a foreign key constraint, calling this method will throw an exception.
     * @param string $name the name of the foreign key constraint to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose foreign is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping a foreign key constraint.
     * @since 1.1.6
     */
    public function dropForeignKey($name, $table)
    {
        throw new CDbException(Yii::t('yii', 'Dropping a foreign key constraint is not supported by SQLite.'));
    }

    /**
     * Builds a SQL statement for changing the definition of a column.
     * Because SQLite does not support altering a DB column, calling this method will throw an exception.
     * @param string $table the table whose column is to be changed. The table name will be properly quoted by the method.
     * @param string $column the name of the column to be changed. The name will be properly quoted by the method.
     * @param string $type the new column type. The {@link getColumnType} method will be invoked to convert abstract column type (if any)
     * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
     * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
     * @return string the SQL statement for changing the definition of a column.
     * @since 1.1.6
     */
    public function alterColumn($table, $column, $type)
    {
        throw new CDbException(Yii::t('yii', 'Altering a DB column is not supported by SQLite.'));
    }

    /**
     * Builds a SQL statement for dropping an index.
     * @param string $name the name of the index to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose index is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping an index.
     * @since 1.1.6
     */
    public function dropIndex($name, $table)
    {
        return 'DROP INDEX ' . $this->quoteTableName($name);
    }

    /**
     * Builds a SQL statement for adding a primary key constraint to an existing table.
     * Because SQLite does not support adding a primary key on an existing table this method will throw an exception.
     * @param string $name the name of the primary key constraint.
     * @param string $table the table that the primary key constraint will be added to.
     * @param string|array $columns comma separated string or array of columns that the primary key will consist of.
     * @return string the SQL statement for adding a primary key constraint to an existing table.
     * @since 1.1.13
     */
    public function addPrimaryKey($name, $table, $columns)
    {
        throw new CDbException(Yii::t('yii', 'Adding a primary key after table has been created is not supported by SQLite.'));
    }


    /**
     * Builds a SQL statement for removing a primary key constraint to an existing table.
     * Because SQLite does not support dropping a primary key from an existing table this method will throw an exception
     * @param string $name the name of the primary key constraint to be removed.
     * @param string $table the table that the primary key constraint will be removed from.
     * @return string the SQL statement for removing a primary key constraint from an existing table.
     * @since 1.1.13
     */
    public function dropPrimaryKey($name, $table)
    {
        throw new CDbException(Yii::t('yii', 'Removing a primary key after table has been created is not supported by SQLite.'));

    }
}
